Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), and the description adds genuinely useful behavior beyond them: results are random from today's set, the set rotates daily and is identical for everyone, calls are non-idempotent, and Listening provides no transcript. It stops short of describing pagination or rate/limit details, so a 4 rather than 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The text is front-loaded with the core purpose and then organized by skill in parallel clauses, so it scans quickly despite its length. It is slightly verbose in enumerating every part range, but nearly every sentence carries actionable information about return content or routing.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description must convey return content itself, and it does so comprehensively for all four skills, including the important absence of answers and the daily random-set behavior. Nothing an agent needs to call this correctly appears to be missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is already 100% and the schema itself documents the part ranges and the omission behavior, so the baseline is 3. The description adds value by mapping each part/skill to the concrete content returned (passage+MCQs, listen_url without transcript, prep/speaking times, word counts), giving the agent a richer sense of what a given parameter value yields.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb+resource ('Get one random CELPIP practice item') and then details exactly what is returned for each of the four skill areas, down to listen_url, visual, timing and word limits. An agent can distinguish this from check_celpip_answers and get_celpip_sample_answers purely from the text.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It states explicitly that no answers are included and names the two alternatives for each case: mark Reading/Listening with check_celpip_answers, compare Speaking/Writing with get_celpip_sample_answers. It also clarifies the 'omit for any part' behavior, leaving little inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.